In order to fine tune the desired flow area through a gas turbine vane ring, adjustments are typically made to the trailing edge of the vane blades. The minimum flow area controls the pressure ratio of the turbine and the mass flow of the engine, and therefore affects the compressor's running line. These adjustments may involve simply bending the trailing edge of a stator vane, cutting back the trailing edge or in the case of a segmented vane ring, vane segment replacement. In order to calibrate the stator ring relative to the gas turbine engine, the flow area of the stator must be determined and is a critical procedure for achieving optimum engine performance as well as optimum efficiency and energy consumption. This requires that the flow area through the vane ring be measured.
Conventionally, the flow area of a stator ring can be determined by use of a flow rig which permits the flow area to be derived from the pressure drop measured across the vane ring. Another conventional method of determining the flow area of a stator ring involves mechanically measuring the dimensions of the throat area.